W: Failed to fetch cdrom://Xubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423)/dists/precise/main/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
W: Failed to fetch cdrom://Xubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423)/dists/precise/multiverse/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
W: Failed to fetch cdrom://Xubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423)/dists/precise/restricted/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
W: Failed to fetch cdrom://Xubuntu 12.04 LTS _Precise Pangolin_ - Release i386 (20120423)/dists/precise/universe/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
E: Some index files failed to download. They have been ignored, or old ones used instead.